Telescopic bow sighting device



March 18, 19 9 J. R. BENFORD ETAL TELESCOPIC BOW SIGHTING DEVICE FiledJan. 3, 1966 V' -QJQ 2 ATTORNEY United States Patent TELESCOPIC BOWSIGHTING DEVICE James R. Benford, Irondequoit, and Herbert D. Korones,

Brighton, N.Y., assignors to Bausch & Lomb Incorporated, Rochester,N.Y., a corporation of New York Filed Jan. 3, 1966, Ser. No. 518,319

US. Cl. 350-10 Int. Cl. G02b 27 /36 5 Claims ABSTRACT OF THE DISCLOSUREThe present invention relates to a telescopic sighting device and moreparticularly it relates to the optical system of a sighting device foruse on an archers bow.

Although telescopic sighting devices for guns are well known in the art,special and distinct problems are encountered when attempts are made touse such devices on on archers bow. Because of the exceedingly hightrajectory angle which an arrow must trace in its flight compared toguns, telescopic gun sights cannot be used easily in archeryinstallations since to elevate the bow (as is usual in shooting at longrange) requires a large angular rotation of the front of the arrow aboutthe anchor point which is usually on the face in close approximation tothe eye. Such rotation would result in the sight not pointing at thetarget, and a counter-rotation of the sight would be necessary torestore the aiming axis. However, such counter-rotation would result inelevation of the eyepoint of the sight so that in order for the archerto see the target, a vertical translation of the sight would berequired. Considerations such as these indicate that the mechanicalconstruction and adjustments necessary to use a standard telescopicsight would be very complicated and costly to assure satisfactoryperformance. In remedying this difficulty, an exceedingly largeelevation adjustment must be incorporated in the sighting device andadditionally other means must be provided to compensate for thecharacteristic stance and position of the shooter with reference to saidtrajectory.

In view of the foregoing statements, it is an object of the presentinvention to provide a telescopic sighting device for an archers bow,said device being compact and convenient to use while providing asuperior aiming capa- :bility, together with a wide range of adjustmentsin both elevation and windage as well as a long eye-relief.

It is a further object to provide an optical sighting device which iscomparatively light in weight and contains few movable parts so thatreliability is increased.

Further objects and advantages will be apparent in the combination andarrangement of parts of the invention by reference to the followingspecification taken together with the accompanying drawing, wherein:

FIG. 1 is a general optical diagram showing one form of the presentinvention;

FIG. 2 is a plan view of an operating unit shown in FIG. 1; and

FIG. 3 is a partial optical diagram showing another form of saidinvention.

Optical sighting devices for use on an archers bow such as describedherebelow may be constructed in various detailed forms, a preferred formthereof being shown in the drawing. As shown in FIG. 1 of the drawing,the telescopic bow sighting device is generally designated by numeral 10and it comprises an objective lens 11 which is aligned on an opticalaxis 12.

According to the present invention, the advantages of a long telescopeare obtained in a short length by folding the optical axis 12 to form anoffset portion which results in a compact and sturdy design. The offsetportion of the optical axis is provided by a system of fiat mirrors, thefirst mirror 14 being located obliquely on said axis near said objectivelens 11. From the first mirror 14, the image rays 15 and 16 arereflected laterally to a second oblique mirror 17, the optical axis 12intersection the second mirror at a point 18 thereon.

The U-shaped offset optical axis portion 19 is extended from point 18toward the eyepiece 13 where a third deviating mirror 20 is located. Onthe U-shaped offset axis portion 19, the objective lens 12 forms animage plane 21.

Advantageously for the purposes of this invention, a two member type oferecting lens system is provided consisting of a pair of erecting lenses22 and 23 which are spaced on opposite sides of the third deviatingmirror 20 for a purpose to be explained hereinafter. The image formed bythe objective at the image plane 21 is reimaged by said erecting lensesat a second image plane 24 located on rearmost leg of the offset axisportion 19.

Rearwardly of the erector lens system is aligned the aforementionedeyepiece 13 which is focused on the image plane 24, the optical axisthereof being substantially aligned with point 27 on the optical axis ofthe objective 11 by interposition of the oblique mirror 25. Thereby thesighting device 10 may be used by either right or left handed shooters,the only change being inversion of the device.

For the purpose of providing the elevation adjustments of the bowsighting device 10, the objective lens 11 is pivotally mounted in anypreferred manner such as shown .at 26 in FIG. 1 so that it may be movedin an are which is centered at point 27. In order to maintain theposition and direction of the optical axis coincident with the point 18on the mirror 17, the first mirror 14 is pivoted at the point 27 on axis12. Said mirror 14 is pivoted about the point 27 at half of the speed ofthe objective 11 by any preferred mechanism such as shown at 29 inFIG. 1. Any suitable mechanism such as there shown may be provided formoving the mirror 14 through an angle 04/2 while the objective is movedthrough the angle a.

This motion permits the objective lens to be pivoted about point 27 soas to scan the vertical meridian while retaining central imagery ofhighest quality. Thus, pivoting the objective avoids the introduction ofoff-axis aberrations which would degrade the image quality, Thehalfspeed compensatory mirror rotation maintains the optical axisrearward of point 27 unchanged during the elevation adjustment,maintaining the fidelity of image quality.

For the purposes of providing windage adjustments in the bow sightingdevice, erector lenses 22 and 23 together with the mirror 20 are mountedas a unit as indicated by the dotted lines 30 which is movably mountedon suitable rails 31 or otherwise to provide lateral motion in ahorizontal direction. By varying the off-axis position of the erectinglenses 22 and 23, the optical axis 12 of the sighting device is deviatedhorizontally through a given angle 5 from normal in much the same manneras if an optical wedge were used. As mentioned above, the erector lenssystem may be of any desired form, but preferably the movable unit 30includes the mirror 20.

A sighting reticle of any preferred configuration is located in thesecond image plane 24. The above-mentioned J lateral movement of theerector lenses moves the image of the target in the second focal plane24, thereby introducing the necessary windage.

In order to compensate for the horizontal olfset between the archers eyeand the bow, it is possible to laterally dispace the eyepiece of thesight thereby deviating optical axis 12 of the sight in towards the eyeof the archer.

A modification of the above-described optical system is shown in FIG. 3wherein the means for elevating the line of sight of the aiming deviceinvolves pivoting of the first mirror per se. In the modified form ofthe invention, image rays from a distant object are directed parallel tothe zero deflection axis 37 and are incident on an inclined flat mirror32.

For the purpose of adjusting the elevation of the line of sight of thebow sighting device, mirror 32 is pivotally mounted at a transversepivot point 33 which is coincident with the face of the mirror and thezero deflection axis 37. In optical alignment with and above the mirror32, an objective lens 34 is mounted in a stationary position so that animage is formed thereby at a subsequent image plane corresponding toimage plane 21 of FIG. 1. The optical axis 37 is deflected along anoffset portion of axis 35 by a fixed inclined mirror 36 which isoptically aligned above the objective lens 34. The remaining parts ofthe modified bow sight are the same as shown in FIG. 1 and have asimilar function. As indicated by the arrow a, the mirror 32 may beadjusted to move through the indicated angle of deflection.

Since the modified optical system Shown in FIG. 3 is much simpler inform than that shown in FIG. 1, the cost thereof is somewhat lower butit necessarily occupies more space.

It is especially noteworthy that the above-described bow sighting deviceis short and compact so that it is handy to use and requires a minimumof mounting space on the bow. In spite of its small size, the sightingdevice is capable of optical performance comparable to largerinstruments, and without optical changes may be adapted for either rightor left hand mountings.

Although only a preferred form of the invention has been shown anddescribed in detail, numerous changes may be made in the form andarrangement of the optical parts without departing from the spirit ofthe invention as defined in the claims herebelow.

We claim:

1. A telescopic bow sighting device characterized by the combination ofan objective lens which is optically aligned on the optical sightingaxis of said device,

an eyepiece spaced therefrom and aligned optically therewith,

an erector lens system optically aligned on a vertically offset foldedportion of the optical axis between said objective and eyepiece,

a reticle located at a focal plane of the optical system between saiderector lens system and the eyepiece,

a first mirror optically aligned with said objective and locatedadjacent thereto which is tiltable about an axis of tilt which issubstantially horizonta and intersects the optical sighting axis, themirror being tiltable so as to deviate the optical axis in a verticalplane along said oflset portion, whereby elevation adjustments areeffected,

a second mirror located on said offset axis portion and aligned toreceive rays from said first mirror and direct said rays through saiderector lens system,

a third mirror aligned on said oflset axis portion adjacent to saiderector lens system, and

a fourth mirror optically aligned between the erector lens system andthe eyepiece so as to deflect the rays coming from the third mirrortoward said eyepiece.

2. A telescopic bow sighting device characterized by the combination ofan objective movably supported for movement in a vertical plane about ahorizontal axis perpendicular to the vertical plane with an angularmotion designated a,

an eyepiece spaced therefrom and aligned optically therewith,

an erector lens system optically aligned on a vertically oflset foldedportion of the optical axis between said objective and said eyepiece,

a reticle located at a focal plane of the optical system between saiderector lens system and said eyepiece,

a first mirror aligned with said objective and located adjacent theretowhich is also tiltable about the aforesaid horizontal axis so as todeviate the optical axis in a vertical plane along said offset portion,the amplitude of angular tilt being a/ 2 simultaneously andunidirectionally with the movement of said objective whereby elevationadjustments are effected,

a second mirror located on said oflset axis portion and aligned toreceive rays from said first mirror and direct said rays through saiderector lens system,

a third mirror aligned on said offset axis portion adjacent to saiderector lens system, and

a fourth mirror optically aligned between the erector lens system andthe eyepiece so as to deflect the rays coming from the third mirrortoward said eyepiece.

3. A telescopic bow sighting device according to claim 1 furthercharacterized by means for holding said erector lens system for movementtransversely of the optical system in a horizontal plane whereby saiderector system additionally performs the function of deviating the imagerays in a horizontal direction to effect windage adjustments in saiddevice.

4. A telescopic bow sighting device as set forth in claim 1 furthercharacterized by said third mirror being located between two componentlenses of said erector system and being mounted as a unit therewith forcommon movement to effect windage adjustments in said device,

5. A telescopic bow sighting device as set forth in claim 4 furthercharacterized by means for adjusting the optical axis of the erectingsystem including means for moving said unit bodily laterally in saidhorizontal plane.

References Cited UNITED STATES PATENTS 683,204 9/1901 Grubb 882.42,949,816 8/1960 Weaver 35010 X 3,081,670 3/1963 Weisglass 882.4 X3,202,047 8/1965 Lawler 350-49 3,302,292 2/1967 Akin 3346.4 3,339,4509/1967 Reed.

FOREIGN PATENTS 769,444 7/ 1954 Great Britain.

DAVID SCHONBERG, Primary Examiner.

T. H. KUSMER, Assistant Examiner.

US. Cl. X.R. 33--46.4

